For power tools I've found Hitachi to be the most robust..believe me..in our game we've destroyed..errr..I mean "tested"... literally hundreds of 7"/9"angle grinders..and Hitachi stand up the best..
. Atlas Copco for air tools... but I'm currently having a good run on Kobe die grinders that are surprising me with their resilience.. cheap enough to throw away instead of repair too...